Spinodal Dewetting Instabilities on Graphene and two-dimensional atomic crystals

We demonstrate theoretically, for the first time, the possibility of spinodal dewetting in heterostructures made of light-atom liquids (hydrogen, helium, and nitrogen) deposited on graphene and other 2D substrates. Extending our theory of film growth on 2D materials [S. Sengupta et al., Phys. Rev. Lett. 120, 236802 (2018)] to include analysis of surface instabilities via the hydrodynamic Cahn-Hilliard – type equation, we characterize in detail the resulting periodic patterns. Both linear stability analysis and advanced computational treatment of the surface hydrodynamics show unconventional, micron-sized (generally material dependent) patterns of “dry” regions. The physical reason for the development of such instabilities on graphene can be traced back to the inherently weak van der Waals interactions between atomically-thin materials and atoms in the liquid, causing the arrest of film growth under normal equilibrium conditions and triggering the associated surface instabilities. These phenomena are robust to some mechanical deformations and are also universally present in doped graphene and other 2D materials, such as monolayer dichalcogenides. Thus, two-dimensional materials represent a universal theoretical and technological platform for studies of spinodal dewetting.